MIL-PRF-20M
TABLE VIII. Group B inspection.
Number of
Number of
Requirement
Test method
sample units to
Inspection
defectives
paragraph
paragraph
be inspected
permitted 1/
Subgroup 1 2/
12
0
Temperature coefficient and capacitance drift
Subgroup 2 3/ 4/
Shock, specified pulse 5/
12
1
Vibration, high frequency 5/
Thermal shock and immersion 5/
1
Subgroup 3 3/ 4/
Terminal strength 5/
1
Resistance to soldering heat
12
Moisture resistance
Subgroup 4 6/
6
1
Marking legibility (laser marking only) 5/
Resistance to solvents (ink marking only) 5/
Subgroup 5
12 minimum per
Life (at elevated ambient temperature)
7/
group
(see 4.6.1.1.1)
1/ A sample unit having one or more defects shall be considered a single defective.
2/ If the manufacturer can demonstrate that this test has been performed five consecutive times with zero
failures, the frequency of this test, with the approval of the qualifying activity, can be performed on an
annual basis. If the design, material, construction, or processing of the part is changed or, if there are any
quality problems or failures, the qualifying activity may require resumption of the original test frequency.
3/ Subgroup 2 and subgroup 3 shall be checked during alternate bimonthly periods.
4/ Subgroup 2 or subgroup 3 tests may be performed on sample units that have been subjected to and have
passed the subgroup 1 tests, when these sampling periods coincide.
5/ If the manufacturer can demonstrate that this test has been performed five consecutive times with zero
failures, this test, with the approval of the qualifying activity, can be deleted. The manufacturer, however,
shall perform this test every three years after the deletion as part of long term design verification. If the
design, material, construction, or processing of the part is changed or, if there are any quality problems, the
qualifying activity may require resumption of the specified testing. Deletion of testing does not relieve the
manufacturer from meeting the test requirement in case of dispute.
6/ Applicable to active for new design styles (ER and non-ER) only.
7/ For non-ER, one defective is permitted. For ER, the number of allowable defectives may vary with the
failure rate level of the part being tested.
4.7 Methods of examination and test.
4.7.1 Visual and mechanical examination. Capacitors shall be examined to verify that the materials, design,
construction, physical dimensions, marking, and workmanship are in accordance with the applicable requirements.
4.7.2 Thermal shock and voltage conditioning (ER parts only) (see 3.6). Capacitors shall be subjected to the tests
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